The present invention relates generally to forage harvesters and, more particularly, is concerned with improvements therein which facilitate easy access to the shearbar on the forage harvester for servicing and maintenance purposes.
In order to maintain the operating efficiency of a forage harvester of the type having a generally-cylindrical rotatable cutterhead with knives spaced about the periphery thereof and an adjacently-positioned, stationary shearbar cooperable with the knives to comminute crop material, it is necessary to maintain a desired uniform clearance between the shearbar and the cutterhead knives, such as from 0.010 to 0.015 inch, as the knives move past the shearbar during rotation of the cutterhead. Therefore, during harvesting season, clearance between the shearbar and the cutterhead knives must be gauged on a periodic basis by the operator and adjustment of the shearbar is made when needed. Otherwise, if the clearance is not checked closely and allowed to become excessive, the result will be unevenness in length of cut and rapid dulling of knives and shearbar. This will in turn cause greater power consumption and more fuel usage in the operation of the forage harvester.
Forage harvesters usually include tandemly arranged front and rear pairs of upper and lower feed rolls located forwardly of the cutterhead and shearbar. It is common for the lower rear roll to have a smooth outer cylindrical surface with a scraper mounted adjacent to and forwardly of the smooth roller for cleaning its surface. As in the case of the shearbar, it is necessary to maintain proper clearance between the scraper and the smooth lower roll in order to prevent buildup of crop material residue which could adversely affect operating efficiency of the forage harvester.
It is, therefore, highly desirable to make the shearbar and cutterhead area and the scraper and lower rear feed roll area of the forage harvester readily accessible so that it will be convenient for the operator to give close attention to the shearbar/cutterhead and scraper/roll clearances. One prior art arrangement on commercial forage harvesters attempts to provide a solution by placing a small door on one side of the cutterhead housing adjacent the shearbar and scraper mounting assembly. By gaining access through the door a feeler gauge may be inserted by the operator to check clearance between the shearbar and the cutterhead knives and between the scraper and the smooth feed roll. This method allows minimal visual contact by the operator with the area being gauged and thereby impedes application of the feeler gauge across the full width of the shearbar. Thus, due to a lack of visual accessibility, the operator usually relies mostly on blind feel with the gauge. As a result, operators using this method have a tendency to neglect making frequent adjustments to the shearbar and scraper clearances due to inaccuracies as well as difficulties encountered during the checking procedure.
The inherent disadvantages of the solution discussed above has lead recently to the incorporation in a commercially available forage harvester of a convenient simple method of gaining quick access to one or both of the critical clearance areas for servicing and maintenance purposes. This apparatus, shown in U.S. Pat. No. 3,985,306, issued on Oct. 12, 1976, in the name of Robert A. Wagstaff et al and assigned to a common assignee, provides a unique arrangement for removing the upper feed roll assembly.
Although the Wagstaff et al invention has been highly successful the trend toward larger forage harvesters has brought about the need for still further improvements due to the attendant increase in bulk and weight of components in heavy duty apparatus. More particularly, the upper feed rolls and mounting mechanisms therefor in larger capacity machines have increased in size and weight to the extent that they have become difficult if not almost impossible in some instances to manually lift out of the operative position.
Another problem that becomes more critical as the size of forage harvesters increase is the tendency of spring biased cylindrical feed rolls to become askew during uneven feeding and thereby causing undesirable racking during operation. A known prior art solution to racking employs a conventional torsion mechanism to apply uniform pressure to the ends of the feed rolls. An arrangement of this type is shown in U.S. Pat. No. 3,444,673 issued in the name of T. Evans on May 20, 1969. Heretofore, a torsion mechanism has not been successfully utilized in a forage harvester having flip up feed rolls of the type exemplified by the Wagstaff et al patent.